Tube bending mandrel

ABSTRACT

A mandrel useful in tube bending operations, the mandrel being constructed-for the most part of plastic or like materials-and includes means whereby the mandrel may be reshaped insuring smooth continuous bends therein free of wrinkles corrugations and the like.

Umted States Patent [1113,580,044

[72] Inventors Edwin A. De V055 [56] References Cited 2550 Pacific Coast Highway, Torrance, UNITED STATES EN S Calif. 90505 Antone Guemim, 3730 w. 132! St. 406,992 7/ 1 889 Burgoln 72/479 awthorne, Calif. 90250 [21] 809313 3 279 237 10/1966 Rader 72/466 [22] Filed Mar-24, 1969 v [45] Patented May 25,1971

[54] TUBE BENDING MANDREL 3 Chums 2 Drawmg Figs ABSTRACT: A mandrel useful in tube bending operations, [52] US. Cl 72/466 the mandrel being constructed-for the most part of plastic or [51] Int. Cl. B21d 9/01 lik'e materials-and includes means whereby the mandrel may [50] Field of Search 72/466, be reshaped insuring smooth continuous bends therein free of 479, 369, 370, 480, 398 wrinkles corrugations and the like.

if 20 17 19 1/ I Z 28 z;

Primary Examiner-Lowell A. Larson Attorneys-Harold L. Fox and Willard M. Graham TUBE BENDING MANDREL This invention pertains to articles facilitating the forming of tubular articles and the like and more particularly to mandrels facilitating the bending of metal tubes, the mandrel being constructed-on the most part of plastic or similar materials-and including means whereby the mandrel may be reshaped facilitating the bending of a tube and incorporating qualities making possible repeated use of the mandrel.

Mandrels of various types and configurations have been proposed and are currently utilized to efiect tube bending operations, however, to the best of Applicants knowledge mandrels, referred to above, are constructed of nonexpandable material and do not include means making possible the reshaping thereof allowing the mandrel to function in the manner described herein.

Briefly, the present invention constitutes a mandrel of elongated configuration, coristructed-for the most part of flexible tooling material-such as polyurethane or the like. The mandrel includes made and female fittings secured to the respective ends thereof. Extending longitudinally of the mandrel is a metal cable terminating in the aforementoned fittings. The female fitting provides means whereby a mandrel rod may be coupled to a mandrel while the male fitting carries means making possible the reshaping of the mandrel. The mandrel is reshaped by applying a compressive force longitudinally of the mandrel, the cable is utilized to effect the reshaping operation. When reshaped, the sidewalls of the mandrel are urged into intimate contacting relation with the walls defining the passageway in' the tube. Thus the mandrel in its reshaped configuration provided adequate and proper support for a tube being bent. The mandrel, in its reshaped configuration confonns to the passageway defined by the tube and, therefore, compensates for differences in manufacturing tolerances inherently present in commercial tubing.

It is an object of the present invention to provide a mandrel functioning to provide adequately and proper support for a tube being formed (bent) thereon.

Another object is to provide a mandrel including means whereby a compressive force may be applied thereto in a longitudinal direction resulting in reshaping of the mandrel thereby insuring smodth continuous bends in a tube being fonned thereon free of wrinkles, corrugations and the like.

Another object is to provide a mandrel having sufficient flexibility enabling a tube to be bent thereon and which may be used repeatedly.

The above objects and advantages of the subject invention will become apparent from the following description of a preferred embodiment of the subject mandrel taken in connection with the accompanying drawing forming a part of this application and in which:

FIG. 1 is a side elevational view of a mandrel as disclosed herein.

FIG. 2 is a sectional view of the mandrel shown in FIG. 1, the section being taken on the line 2-2 of the latter FIG.

Referring to the drawing, a mandrel of the type disclosed herein is shown in FIG. 1 and is identified in its entirety by the numeral 11. Major components of the mandrel 11 includes a body portion, male and female fittings and a cable member 12, 14, l6, 17, respectively.

The body portion 12 is constructed of a flexible tooling material constituting core and skin portions 18 and 19, respectively, of integral construction, specifically the mandrel is constructed-for the most part-of polyurethane material (plastic) of various degrees of hardness. A bore 20, having a coaxial relation with respect to the body portion 12, extends therethrough and provides passage for the aforementioned cable 17. The skin portion 19 has qualities rendering it tough, hard and wear resistant thereby providing a suitable cover for the core portion 18. The core portion 18 having qualities rendering it flexible and reshapable and enabling the mandrel 11 to function in a desirable and efficient manner. Regarding the integral construction of the body portion 12, it is assumed that the portion 12 is fabricated by a molding operation, further it is assumed that the portion 12 is cast in a mold having a high degree of heat conductivity. Under the condition described above, the skin portion will inherently be provided with a tough, hard skin for reasons well known to those skilled in the art.

The fitting members 14 and 16, generally of cylindrical configuration, are cast in the body portion 12. As cast in the portion 12, the axes of the members 14 and 16 have an aligned relation and coincide with the axis of the portion 12 as shown by the line x-x in FIG. 1. The relationship of the fitting members 14 and 16 in the portion 12 is further characterized in t hat the outer end of the member 16 has a flush relation with the end of the body portion 12 in which it is located. The outer end of the member 14 extends from the end of the portion 12 in which it is positioned and serves a purpose that will become apparent as the disclosure progresses. In this respect, the inner threaded end of the member 14 is covered with a coating of electricians tape 20 or the like prior to it being cast in the body portion 12. The tape 20 functions to preclude the polyurethane from entering the threads during the casting operation. It also functions to allow relative movement between the member 14 and portion 12 in a manner that will become apparent as the disclosure progresses.

Referring further to FIG. 1 it will seem that the members 14 and 16 are hollow having circular bores formed therein as indicated by the numerals 21 and 22. The outside surface of the male member 14 is threaded as indicated by the numeral 23 while the bore 22 is internally threaded as indicated by the numeral 24. The memberl6 is further characterized in that its outer surface is serrated as indicated by the numeral 26, the serrations functioning to maintain the fixed relation of the member 16 in the portion 12.

Extending through the body portion 12 through the bores 20, 21 and 22 is'the a cable 17. The length of the member 17 varies according to the specific mandrel 11 with which it is to be used or specifically according to the length of the portion 12. The member 17 carries ball-type fittings 27 and 28 brazed or swaged on the respective ends thereof. The member 17 constitutes a braided or woven steel cable and, therefore, it in cooperation with the fittings 27 and 28, constitutes a nonexpandable assembly. In the assembled relation of the mandrel 11, the fitting members 27 and 28 are bottomed on and in the fittings 14 and 16, respectively as shown in FIG. 1.

Referring further to FIG. 1, in the assembled relation of the mandrel 11, a collar or washer 29 is received on the extending portion of the male fitting and is positioned adjacent the body portion 12. Received on the extending portion of the member 14 (threads 23) is a lock nut assembly 31 comprising lock and jam nuts 32 and 33, respectively.

Various components comprising the mandrel 11 having been described a better understanding thereof will be forthcoming from the following discussion of a tube bending operation.

The mandrel 11 is first secured to a mandrel rod (not shown) utilizing the internal threads in the fitting 16 to accomplish this result. With the mandrel rod connected to the mandrel, the latter is urged into a tube (not shown) which is to be bent. Should'it become apparent, either before or during a tube bending operation, that the mandrel does not or will not provide adequate and proper support for the aforementioned tube, the cable 17 is shortened resulting in the reshaping of the body portion 12. In this respect, shortening of the cable 17 applies a compressive force longitudinally of the portion 12. In as much as the portion 12 is constructed of a noncompressible material it assumes a new shape in which the portion 12 contacts and conforms with the walls defining the passageway in the tube. Thus adequate and proper support is providedfor the tube during the forming (bending) operation. In as much as the body portion is constructed of a material having elastomeric properties (polyurethane), thus it may be returned to its original size by reversing the above operation. Accordingly, the portion 12 assumes its original configuration and entry of the portion 12 in the tube is easily effected.

As previously mentioned the skin portion 18 of the mandrel has qualities imparting hard and tough characteristics thereto. Accordingly the above operation results in very little wear enabling the mandrel to be used repeatedly in effecting tube bending operations. In contrast the core portion 18 is relative flexible and reshapable resulting in an increase in the lateral direction. Thus it will be seen that a mandrel is disclosed consisting of a soft core portion, a hard tough outer surface and including means for reshaping the mandrel, these features cooperating to insure maximum forming ability and good wear resistance qualities referred to above.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise the preferred form of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

We claim:

1. A mandrel useful in effecting a tube bending operation,

comprising:

a. an elongated body portion of cylindrical configuration fabricated of flexible plastic material and having'a coaxial bore extending therethrough;

b. a metal cable extending through said bore in said body portion;

c.-threaded means cooperating with said cable enabling the latter to be shortened or lengthened thereby changing the configuration of said body portion.

2. Apparatus as set forth in claim 5:

a. in that said body portion constitutes polyurethane plastic.

3. Apparatus as set forth in claim 2:

a. in that said metal cable constitutes a woven steel cable. 

1. A mandrel useful in effecting a tube bending operation, comprising: a. an elongated body portion of cylindrical configuration fabricated of flexible plastic material and having a coaxial bore extending therethrough; b. a metal cable extending through said bore in said body portion; c. threaded means cooperating with said cable enabling the latter to be shortened or lengthened thereby changing the configuration of said body portion.
 2. Apparatus as set forth in claim 5: a. in that said body portion constitutes polyurethane plastic.
 3. Apparatus as set forth in claim 2: a. in that said metal cable constitutes a woven steel cable. 